Customarily, a former is provided with a former roller, by use of which a web of material, brought in to the former from a side, is rerouted downwardly into the former. The former roller is driven by a motor at a regulated speed for avoiding imposing a tensile load on the web of material. The roller rotates with a circumferential speed matched to the conveying speed of the web and avoids the exertion of a tensile load on the web.
Errors can occur in the course of processing the web of material in the folding apparatus with the result being that a considerable amount of material is conveyed into the folding apparatus, which material can no longer be correctly processed in the folding apparatus and which material thus piles up before the folding apparatus, and a device which is located upstream of it, such as, for example a printing press from which the material is supplied, can be brought to a stop. Such a pile-up of material can result in damage to the folding apparatus. To limit the amount of material which can pile up at one location, it is generally known to provide cut-off devices along the conveying path of the material, which devices cut off the web of material in the event of a malfunction. If the leading end of the web of material, which leading end is being created in the course of the cut-off, is successfully moved out of the conveying path, this results in a limitation of the amount of material which can pile up in the folding apparatus, and the danger of damage is thereby reduced. On the other hand, because of the cut-off, the tension in the web of material, which tension is present during normal operations, collapses, so that pile-ups of material can result at other locations, in particular in a device upstream of the folding apparatus, such as a printing press.
DE 44 28 593 A1 describes a device for measuring and regulating the tension in a web in a former area. In the course of the use of this device, the force of the web acting on the former is detected and the former roller is controlled as a function of this force.
DE 41 37 818 A1 discloses a device for setting the web tension. A number of revolutions of traction rollers arranged downstream of a former can be mutually regulated.
DE 297 23 888 U 1 discloses a linear former with a driven former inlet roller.
A device for folding webs of material is known from U.S. Pat. No. 5,449,156. A web tension is changed by changing the number of revolutions of a traction roller.